Significant coronary artery disease detected by amyl nitrite and systolic time intervals

The relation between changes in left ventricular systolic time intervals with amyl nitrite (AN) inhalation and the severity of coronary artery disease (CAD) was evaluated in 77 patients who underwent catheterization because of chest pain. In 25 subjects with normal coronary angiograms (control group), AN inhalation increased the ejection time (ET), shortened the prejection period (PEP) and increased the ET/PEP markedly. In the 52 patients with CAD (CAD group), the ET/PEP changed insignificantly after AN. The difference between the 2 groups was significant (p < 0.001). At cardiac catherization, the increase of left ventricular dP/dt after AN in the control group was significantly larger than that in the CAD group. Although a positive correlation between changes in ET/PEP with AN and ejection fraction at rest was noted in patients with 1-vessel CAD, no such correlation was noted in those with multivessel CAD. This suggests that factors in addition to pump function, such as the degree of CAD, influence the effect of AN inhalation on systolic time intervals. When an increase of less than 30% in ET/PEP occurs with AN Inhalation, the presence of significant CAD can be detected with a sensitivity of 92%, a specificity of 84% and the predictive value of 92%. The AN inhalation test is safe and simple, and thus could serve as a stress test for evaluating the presence and severity of significant CAD.